请问这个怎么写！

[飞扬残月]

<%

set rs = server.createobject("adodb.recordset")

sql = "select sum(h5-h7-h9)/100 as 2112,sum(m5-m7-m9)/100 as 2651,sum(f5-f7-f9)/100 as

2652,sum(l5-l7-l9)/100 as 2653,sum(nc5-nc7-nc9)/100 as 2656,sum(p5-p7-p9)/100 as

2655,sum(n5-n7-n9)/100 as 2551,sum(z5-z7-z9)/100 as 2552 from bmxs "
rs.open sql,conn,1,1

%>现在的问题是，我想求和，就是2112，2651，2652，2653，2655，2656，2551，2552相加的和是多少，怎么做这个，还有，如果2651的数据为空，怎样赋值给他让他为零然后再求和！求和过后，我想知道没个所占的白分比是多少，有怎样表达？谢谢，在线等，分不够再加